Methods to make nanoparticles for energy storage devices, such as lithium metal phosphates, use solid-state reactions at high temperatures resulting in nanoparticles that are heterogeneous in size and morphology. These methods, therefore, have to incorporate an additional milling or grinding step in attempts to reduce and make more uniform the nanoparticle size distribution. Non-uniform nanoparticle size and morphology increases stress concentrations and de-stabilizes charge distribution in energy storage devices.